The present invention relates to a retractor for a seatbelt and, in particular, to an improved retractor for a seat belt which is mounted in the interior portion of a seat back of a seat of a reclining type for use in a vehicle or the like.
Conventionally, a retractor of a seat belt device for holding an occupant of a vehicle in a seat of the vehicle in safety is well known. The retractor is a device which, when a seat belt is not in use, pulls in a webbing automatically and also, when the seat belt is in use, allows the webbing to vary freely in length.
Recently, for example, Japanese Patent Unexamined Publication No. Hei. 8-80807 and the like teaches a seat belt device comprising a retractor of the above-mentioned type in which the retractor is mounted in the interior portion of a seat back of a reclining type seat in a vehicle or the like. In addition, the seat belt device further comprises a vehicle body acceleration sensor which can be operated even when the seat back (a support of the back of the seat) is inclined at any different positions.
Referring in particular to the conventional seat belt device 70, as shown in FIG. 25, one end of a webbing 90 is held by a seat-built-in type retractor 80 disposed in the upper portion of a seat back 73 of a seat 71 of a reclining type in such a manner that it can be taken up and drawn out, whereas the other end of the webbing 90 is supported by an anchor plate 74 fixed to a vehicle body or to a seat base portion.
In addition, a through tongue 75 disposed in the middle portion of the webbing between the retractor 80 and anchor plate 74 is engaged with a buckle 76 erected almost in the central portion of the vehicle body, thereby being able to hold an occupant in the seat 71 of a reclining type.
The seat back 73 of the seat 71, which is supported by a reclining device 78 so as to be inclinable back and forth with respect to the back-and-forth slidable seat sitting portion 72, s adjusted to inclined positions which vary in angles according to the physiques of occupants. On the other hand, in the structure of the vehicle body acceleration sensor of the retractor 80, for example, such acceleration sensor is supported so as to be pivotable about a rotation axis extending in parallel to the adjusting axis D of the seat back 73. Accordingly, the vehicle body acceleration sensor can be operated even when the seat back 73 is adjusted in the angle and is thus held at different inclined positions.
However, there are still left some problems which should be solved in the above-mentioned conventional seat belt device 70. In the seat belt device 70, one end portion of the webbing 90 is disposed on the swing end side 73a of the seat back 73 of the reclining type, but the other end portion 73b is supported by the anchor plate 74 fixed to the vehicle body or seat base portion. Due to this structure, if the seat back 73 is inclined back and forth, the webbing 90 can be taken up or drawn out with respect to the retractor 80.
In the seat-built-in type retractor 80 which incorporates therein at least the vehicle body acceleration sensor, if the seat back is inclined further beyond the allowable angle of the vehicle body acceleration sensor, there is possibly actuated an emergency lock mechanism which prevents the webbing 90 from being drawn out.
Thus, in the above seat belt device 70, as shown by imaginary lines FIG. 25, when the seat back 73 is inclined forwardly, the webbing 90, the other end portion of which is fixed to the vehicle body or seat sitting portion, is wound into the retractor 80. Moreover, if the seat back 73 is inclined forwardly further beyond the allowable angle of the vehicle body acceleration sensor, then the emergency lock mechanism is actuated to thereby prevent the webbing 90 from being drawn out.
And, even if the occupant tries to raise the seat back 73 again, because the emergency lock mechanism is in operation at the position where most of the webbing 90 is wound into the retractor 80, it becomes impossible to draw out the webbing 90 from the retractor 80. That is, there is a possibility that the webbing 90 is subjected to the tension and then the seat back 73 can not be raised.
In addition to this, when the seat 71 is slid forward from the state shown in FIG. 25, the anchor plate 74, as shown by imaginary lines in FIG. 25, is moved to a position behind the seat sitting portion 72. In this case, there is a possibility that, if the seat back 73 is inclined backwardly, then the emergency lock mechanism is actuated, so that, similarly to the above case, the seat back 73 cannot be raised.